We present the market research tool ShelfAware which implements a virtual test store of a grocery store using gaming technology available on PCs. The purpose of ShelfAware is to study user behavior including choice studies of grocery shoppers in a virtual environment, and hence give evidence on how customers would behave in a real store. Gaming technolgy is used for implementing a realistic looking replica of a real-world grocery store. Modelling aspects when designing or modifying virtual stores are addressed. We present results from usabilitiy studies of ShelfAware. Two issues are of special interest: (1) Are novice users capable of operating the tool, and (2) how does the behavior in a real store and the behavior in a virtual store compare. A real world user study with about 600 grocery shoppers of a selected grocery store was performed.